org.apache.cassandra.utils
Class StreamingHistogram

java.lang.Object
  org.apache.cassandra.utils.StreamingHistogram

public class StreamingHistogram
extends java.lang.Object

Histogram that can be constructed from streaming of data. The algorithm is taken from following paper: Yael Ben-Haim and Elad Tom-Tov, "A Streaming Parallel Decision Tree Algorithm" (2010) http://jmlr.csail.mit.edu/papers/volume11/ben-haim10a/ben-haim10a.pdf

Nested Class Summary

static class

StreamingHistogram.StreamingHistogramSerializer

Field Summary

static StreamingHistogram.StreamingHistogramSerializer

serializer

Constructor Summary

StreamingHistogram(int maxBinSize)
Creates a new histogram with max bin size of maxBinSize

Method Summary

java.util.Map<java.lang.Double,java.lang.Long>	getAsMap()
void	merge(StreamingHistogram other) Merges given histogram with this histogram.
double	sum(double b) Calculates estimated number of points in interval [-inf,b].
void	update(double p) Adds new point p to this histogram.
void	update(double p, long m) Adds new point p with value m to this histogram.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serializer

public static final StreamingHistogram.StreamingHistogramSerializer serializer

Constructor Detail

StreamingHistogram

public StreamingHistogram(int maxBinSize)

Creates a new histogram with max bin size of maxBinSize

Parameters:

maxBinSize - maximum number of bins this histogram can have

Method Detail

update

public void update(double p)

Adds new point p to this histogram.

Parameters:

p -

update

public void update(double p,
                   long m)

Adds new point p with value m to this histogram.

Parameters:

p -

m -

merge

public void merge(StreamingHistogram other)

Merges given histogram with this histogram.

Parameters:

other - histogram to merge

sum

public double sum(double b)

Calculates estimated number of points in interval [-inf,b].

Parameters:

b - upper bound of a interval to calculate sum

Returns:

estimated number of points in a interval [-inf,b].

getAsMap

public java.util.Map<java.lang.Double,java.lang.Long> getAsMap()